External grinder



June 21, 1932. c. T. RAULE EXTERNAL GRINDER Filed July 31, 1950 2 SheetsSheec 1 Patented June 21, 1932 UNITED STATES CLIFFORD '1. RAULE, or BROOKLINE, PENNSYLVANIA EXTERNAL GRINDER Application filed July 31,

My invention relates to external grinders for the precision grinding of a large quantity of like hollow articles and includes subject matter divisional from my copending application, Serial N 0. 136,771 entitled Multiple external grinder, filed September 21, 1926.

A purpose of my invention is to provide a multiple external grinder of the character indicated well adapted to the needs of service and easy and inexpensive to manufacture.

A further purpose is to provide a multiple external grinder of the character indicated with mandrel mechanism for holding individual hollow work pieces during grinding.

A further purpose is to combine work loading and work unloading mechanism with a desirable form of work holding mechanisms that follow one another around a grinding wheel, presenting successive work pieces to the wheel.

Further purposes will appear in the specification and in the claims.

I have elected to illustrate one only of the different forms of my invention, selecting a form that is practical and efficient in operation and which well illustrates the principles involved.

Figure 1 is a framentary plan view illustrating one embodiment of my invention, work holding mechanism being broken away to disclose the work pieces.

Figure 2 is a fragmentary section taken upon the line 22 of Figure 1.

.Figure 3 is an enlarged sectional detail taken upon the line 33 of Figure 1.

Figure 4 is a diagrammatic view to illustrate the relative positions of certain parts throughout the cycle of operations.

Like numerals refer to like parts in all figures.

Describing in illustration and not in limitation and referring to the drawings I show a stationary frame 10 upon which is formed a central bearing 11 shouldered at 12 to receive the hub 13of a rotatable table 14 which carries work pieces 15 around a grinding wheel 16 as later described.

At any convenient point in or upon the frame I mount a motor 17 connected by belt 1930. Serial No. 471,935.

18 with pulley 19 upon the shaft 20 shown as supported in stationary bearings 21 .and 22. The shaft has a hand-clutch connection at 23 with a gear'24 that engages aninternal gear 25 rigid with thetable to rotate the table. 1

A gear 26 upon the shaft 20 engages a gear 27 upon a shaft 28 journaled Within the bearing 11 to rotate the shaft and with it to rotate the grinding wheel 16 mounted upon the top of the shaft.

The grinding wheel cooperates with the work-holding devices which 'aresupported upon. the table at uniformly spaced intervals, thewheel operating at the same time upon all of the pieces of work following one I another around the wheel between positions of charging and discharging.

In order to protect against grinding too much at the same part of the wheel width, the wheel is traversed (reciprocated) axially while it is continuously rotated.

This traversing is secured by spiral gearing 30 connecting the shaft 20 with the shaft 31, a Worm 32, worm gear 33 and cam 34 upon the shaft 35 of the worm gear, whereby the shaft 28 and the grinding wheel carried by it are vertically reciprocated by engagement between the bottom of the shaft and the cam 34.

The gear 27 is given sufiicient length :of tooth to continue in engagement with the gear 26 at all times notwithstanding the traversing movement. I

The table 14 is provided at intervals about its circumference with a plurality of'bearings 39 within which are supported shafts 40, carrying the gears 41 and 42 respectively above and below the bearing, the-gears 42 of the difierent units all meshing in a-large stationary gear 43, so that the rotary movement of the turntable rotates the vertical'shafts' 40 in'the turntable.

The gears 41 and 42 are rigidly mounted upon the shafts 40 which are extended above the gear 41 to form a pivot 44 for the hub por tion 45 of the work holding units 46. r

The tubular work 15 is heldduring the grinding operation upon mandrels 47 as best seen in Figure 3. I

from the cente-riof the grinding wheel, push- The mandrel 47 has a splined mount in a rotating sleeve member 48 being adapted to slide longitudinally in the sleeve but not to rotate with respect to the sleeve.

The sleeve 48 is j ournaled in the lower arm of the member 46 and rotated in any suitable Way, being shown carrying a gear 49 meshing with thegear 41 keyed to the shaft 40.

The mandrel carries a downwardly extending stem 51 which is surrounded within the sleeve by a spiral-spring "that presses the mandrel upwardly. At its lower end the stem is provided with a. flange orhead 52' which is adapted to be engaged and pulled downwardly during the rotation of the turntable'byanxarcuate cam 53 upon the stationary-fr'aJn-e'structure of the machine.

Figure 3. shows the mandrel as having just receivedanew-work piece 15, the downwardlya'presented'head 52 of the mandrel having run 05 an end portion 54 of the cam permitting theqmandreLto spring up until the upwardly: directed face of-thework piece stops against; the downwardly directed face r0- tatablebearing;- member 55 having roller bearing support at 56 from upward movement. 1 1

Desirably-the upper end of the mandrel 47 is'suitably tapered at 57 to more easily registerrwith the=interior of the-work piece.

By' this... construction the rotation of the table carries-the workholding units bodily about the axis ofrthe table while;rotating the mandrelsand work pieces: upon their. own

Thev worki-holdingz'unitsare free to swing about the upwardextension 44 of the shaft 40, permitting the workto be swung toward or away from the: grinding wheel as desired.

Recurring :to Figures 1, 2 and 3; at any suitable point at a distance from the shaft extension 44the lower arm of the member 46 is provided with a radial :or side extension 58 whose terminal-59 'engagesthe inner surface 60 of a feed cam 61 surrounding all or the majorportionof-the path or orbit of movement travelled by the'work-holders and work and; thisicam maybe used. as in Figures 1, 2 and 3 to determine the distanceofthe work ing the work in toward the .center to effect the grindinga and allowing the work to move outwardly-for;removal. when the grinding has beiencompleted.

\Vith' the direction of grinding. wheel m'ovementzgiven by the arrow in Figure 1,.the pressure of the grinding wheel. against the work as well as the pressure of the teeth of the 'gear'41 flgflinsttllf teeth of-the' gear 49 will tendto throw the: member 46 away from theigrinding'wheel; maintaining the terminal 59in engagement withthe cam. For additional assuranceof this-tendency of the work to m'ove outwardly-toward thewcam I show a tension spring 62 pulling upon thearmnu the opposite side of the center of shaft 40 with respect to the work.

The terminal 59 is shown as capable of adjustment by threading into the extension 58 as at 63 lock nuts 64 being shown for adj ustably fastening theterminal in its set positions- The cam 61 is shown conventionally as supported from a frame rim 65 by studs 66 which pass through the rim and are adjustably held to place by inner and outer nuts 67 and 68.

The cam is shown as sectioned at 69 at a point beyond that at which grinding is completed to permit the slight variation of length incident to adjustments in the radial position of the cam and to. permit making it up in several parts.-

In practice the cam need not extend all the way around or the joint may be an ordinary lap oint.

Automatic feeding of the work tothe machine is provided by rotor arms 7O terminating in springclamps 71.

The rotor member is mounted upon a shaft 72 that is driven through spiral gears 73, shaft 74 and spiral gears'7 5, one of which is mounted on the shaft 20.

Asemi-circular gauge 76 below the circular path of the clamps 71 is used to exactly register the work pieces vertically in the clamps. The work pieces are put into the rotating clamps by hand and exactly positioned vertically by pushing down to the gauge 7 6.

The travelof the feed clamps is-synchronized with that of the work-holders upon the turn-table, successive work pieces being presented by the successive clamps to position between and coaxial with the mandrel 47 and thrust bearing .56 of the successive workholding members 46 as these members successively reach the loadingposition.

VV-hen this position is reached the axisof the work piece in the clamp lies momentarily iniine with the common axis of the mandrel and thr-ust bearin-g, the mandrel having been lowered some time before by reason of the bottom of the flange or head 52 riding along the under. surface of the cam 53, the work piece being at a higher level than the top of the mandrel. v v

At charging position'the flange or head 52 comes to a steep rise'54 on the cam 53 and asa result the mandrelmovesupwardly under the action of the spring 51, the upper end ofthe mandrel entering the perforation 77 through the work piece 15, lifting the work' piece out oftheclamp and into engagement witlrthe thrust. bearing 55.

.As the work progresses along the cycle of operations from'the point of loading it is inwardly pressed againstthe grinding wheel atithefsame time that it is rotated andis carinward-feedidepends. upon thesetting of the camand 'thesetting of theterminals 597-; both of which are preliminarily designed to suit the work and are capable of adjustment.

The cycle of operations is shown diagrammatically in the hypothetical curves A, B and C of Figure 4. V

In these curves the abscissze represent the angular or circumferential position around the machine or, putting it differently, represent successive positions along the common circumferential orbit of the work pieces, each point of any of these curves corresponding to a definite angular position about the axis of the machine.

The ordinates in curve A represent the distances of the inner surface of the feed cam from the outer surface of the grinding wheel, and the ordinates of the curves B and 0 rep.- resent, respectively, the elevation of the work piece and the elevation of the mandrel.

The cycle of operations is illustrated for a single unit and takes place on successive work pieces at each work-holding member during the successive circuits of the machine.

At the line b the work piece 15, which has just been positioned axially between the mandrel 47 and the bearing member by one of the clamps 71 is engaged by the released mandrel which moves upward between the points a and 0 when the head 52 is on the steep portion 54 of the cam 53, enters the perforation in the work piece and lifts the work piece into engagement with the downwardly directed face of the thrust bearing member 55.

The feed cam is, at this time, relatively far from the grinding surface of the wheel so that the work piece is positioned well away from the wheel. Between the lines d and e the feed cam is guiding the work rapidly inward toward the wheel.

There is some variation in the initial sizes of the work pieces, and therefore some variation in the position represented by the line 7 (Figure 4) at which the work engages the wheel.

Normal feed begins at the line 6 and the position 7 of engagement between the work piece and the wheel will be variant with the different work pieces according to the slight variation in the outside diameter of the work pieces.

Between the lines 6 and g the inner surface of the fixed feed cam is located progressively nearer to the grinding surface of the wheel and the grinding operation all takes place in that part of the orbit which is between these lines.

At the line 9 the feed is over and the feed cam begins to offset from the surface of the wheel. This offsetting of the feed cam is indicated as being complete by the time the line it is reached.

At the line j, which is somewhat after the completion of the feeding operation the work-holder brings the work piece into a forked guideway 7 8 (Figure 1).

At the line k which is desirably substantially coincident with the line 1', the head 52 upon the lower end of the stem of the man- I drel engages the downwardly sloping portion 79 of the cam 53, the head 52 riding down the slope 79 between the lines j and m pulling the mandrel downward and leaving the work piece at the line 12. in the discharge guideway 78 along which it is progressed to be ultimately discharged by the succeeding work pieces.

At the line 'b which is coincident with the line b the cycle begins anew, a new work piece being inserted into proper position above the mandrel and below the thrust bearing 55, and the mandrel moving up under the action of its spring 51 when the head reaches the portion 54 of the cam 53.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and scope of my invention. 1 7

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. In an external 1 grinder, a grinding wheel, a turntable coaxial with the wheel, bearings spaced circumferentially around the turntable and adapted to move toward and away from the grinding surface of the wheel, a rotatable sleeve in each bearing, a mandrel upwardly spring-pressed and slidably mounted in each sleeve and not rotatable with respect thereto, a second sleeve rotatably mounted upon the bearing and coaxial with and spaced from the first sleeve, common feed means operative along a portion of the orbit common to the spaced bearings to progressively feed the successive bearings toward the wheel and means common to the different mandrels operating with the mandrels at one portion of the orbit to retract themandrels to disengage the work.

2. In a multiple external grinder for tubular work pieces, a central grinding wheel,

mandrel work holders spaced around the wheel having axes parallel to the wheel axis and a common orbit around the wheel, in combination with mechanism for progressively feeding the mandrels laterally toward the wheel throughout a considerable and grinding portion of their common orbit, for moving the mandrels laterally outwardly from the wheel after the grinding operation is complete for another portion of the common orbit, for discharging the work pieces from the mandrels while they are outwardly from the wheel at a definite position of the common orbit, and a device adapted to insertnew work pieces at another, definite positionof the orbit into the successive work-V holders for grinding.

3. In an external grinder a grinding wheel, mandrel chucks spaced along an adjustable common orbit around the wheel, movable means for supporting the chucks and for moving them about the orbit and means for successively closing the chucks as they successively pass a pointoftheir common orbit in combination with a loading device adaptedto hold and carry a Work piece and mechanism synchronizing the loading device, to bring 1ts loads successively 1nto registrywith the axes of the successive chucks at the loading position of the orbit.

4. In a multiple external grinder for grinding tubular work pieces, a grinding .wheel, planetary mandrel work holders guided along a common orbit around the wheel, and means for moving the workholdel's aboutthe orbit in combination with a rotorsweep adapted to receive the work successively in some positions of the sweep, synchronized with the travel of the work-hold ers along the orbit and adapted to successively sweep the work pieces of the column into registry with the travelling work holders, and mechanism for transferring the work from the sweep to theholder.

CLIFFORD T. RAULE. 

